1. Field of the Invention
The present invention relates to a compact measuring apparatus capable of measuring depths of water and altitudes with a single pressure sensor.
2. Description of the Prior Art
To measure depths of water for divers, various types of decompression meters, i.e., bathometers have been proposed in which a pressure sensor is incorporated. For instance, a wrist-carried decometer capable of measuring depths of water and also time of dives is described in U.S. Pat. No. 4,005,282 issued to Jennings. It is very useful for divers to carry wristwatches into which the above-described pressure measuring apparatus is incorporated.
Although these wristwatches employing the bathometers are fairly convenient for persons who dive many times on their business or hobby, persons other than these diving persons scarcely utilize such bathometers, or rather require meters capable of obtaining altitude information for hiking and hang gliding.
Moreover, the above-described divers also require the altitude information in their usual life.
To acquire such an altitude information, complex measuring devices are required, as described in, for instance, U.S. Pat. No. 3,958,459 to Shimomura.
No prior art meter has been ever proposed to measure not only depths of water, but also altitudes by employing a single pressure sensor. Even if a measuring device could be equipped with measuring functions for both depths of water and altitudes, it would become bulky and expensive. In addition, inconvenient switch operation is necessarily required to select the altitude measurement and the measurement for depths of water.